Axial flow machine having an asymmetrical compressor inlet guide baffle

ABSTRACT

An axial flow machine having an asymmetrical air inlet and, downstream therefrom, a compressor having an inlet guide baffle composed of guide vanes is characterized in that at least some of the guide vanes of the inlet guide baffle have a vane profile and/or an angle of attack that deviate(s) from the remaining guide vanes. The inlet flow angle of the first compressor stage is hereby evened out circumferentially symmetrically. This is accomplished in that the different inlet angles resulting at various circumferential positions of the inlet guide baffle due to the asymmetry of the air inlet, are influenced by selective profiling and/or by selectively modifying the angle of incidence of individual guide vanes in such a way that a circumferentially symmetrical outflow angle from the inlet vane ring results. In this way, the circumferential distortions caused by the asymmetrical air inlet are minimized and, thus, circumferentially symmetrical inlet conditions are passed onto the first compressor stage, which results in an improved stability and an enhanced efficiency of the compressor.

The present invention relates to an axial flow machine having an asymmetrical air inlet and, directly downstream therefrom, a compressor having an inlet guide baffle composed of guide vanes.

BACKGROUND

Such axial flow machines having an asymmetrical air inlet are used as core engines in the case of turboprop or helicopter engines, for example. The asymmetry of the incident flow of the first compressor stage can cause problems related thereto, which can lead to a partial flow separation at this vane stage, along with the surging and efficiency loss resulting therefrom.

For stationary gas turbines, the European Patent Application EP 1 508 669 A1 teaches that, by forming different profile curvatures of at least two inlet guide vanes, it is possible to increase the efficiency of a stationary gas turbine. The increase in the efficiency is achieved by reducing the flow losses at the inlet guide baffle.

SUMMARY OF THE INVENTION

It is an object of the present invention to avoid the disadvantages of the known related-art approaches and to devise an improved approach for achieving the most symmetrical possible incident flow of the first compressor stage in the case of an axial flow machine having an asymmetrical air inlet.

The present invention provides an axial flow machine having an asymmetrical air inlet and, downstream therefrom, a compressor having an inlet guide baffle composed of guide vanes. Advantageous embodiments and refinements of the present invention are delineated in the dependent claims.

An axial flow machine having an asymmetrical air inlet and, downstream therefrom, a compressor having an inlet guide baffle composed of guide vanes is provided in accordance with present invention, whereby at least some of the guide vanes of the inlet guide baffle have a vane profile and/or an angle of attack that deviate(s) from the remaining guide vanes. The inlet flow angle of the first compressor stage is hereby evened out circumferentially symmetrically. This is accomplished in that the different inlet angles resulting at various circumferential positions of the inlet guide baffle due to the asymmetry of the air inlet, are influenced by selective profiling and/or by selectively modifying the angle of incidence of individual guide vanes in such a way that a circumferentially symmetrical outflow angle from the inlet vane ring results. In this way, circumferential flow distortions caused by the asymmetrical air inlet are minimized and, thus, circumferentially symmetrical inlet conditions are passed onto the first compressor stage, which results in an improved stability and an enhanced efficiency of the compressor. There may, for example, be a main guide vane group in the guide baffle that has only some individual vanes that differ from those of the group.

One advantageous specific embodiment of the present invention provides that some or a plurality of the guide baffles following the inlet guide baffle have at least some guide vanes having a vane profile and/or an angle of attack that deviate(s) from the remaining guide vanes. Due to the asymmetric profiling of the intermediate guide baffle following the inlet guide baffle, any residual asymmetries of the flow possibly still existing may be further reduced following the first stage.

One advantageous specific embodiment of the present invention provides that individual guide vane groups have a vane profile and/or angles of attack that deviate(s) from the remaining guide vanes. This makes possible an efficient production and the cost savings associated therewith. The guide vanes may be configured in a plurality of groups having different geometries, for example.

One advantageous specific embodiment of the present invention provides that the guide vanes of the particular guide vane groups have vane profiles and/or angles of attack that deviate from one another.

Another advantageous specific embodiment of the present invention provides that all guide vanes be differently profiled and/or have a different angle of attack. In this case, this means that each individual vane may be profiled in a specific way, or that the individual vanes may be re-staggered, thereby permitting an adaptation to the asymmetric incident flow.

Another advantageous specific embodiment of the present invention provides that the guide vanes have an adjustable design. The desired effect may likewise be achieved by variably adjusting at least individual vanes or vane groups, since this makes it possible to quasi selectively re-stagger individual vanes. Here, the advantage is also derived that, in the case that the flow conditions change, it is possible to correct the individual orientation of the guide baffle.

Another advantageous specific embodiment of the present invention provides that the guide vanes be formed on the inlet side of a fixed component and, on the outlet side, of a pivoted component. In this manner, even individually differing profilings may be created for individual vanes of the guide vane baffle when some or all of the vanes are suitably adjusted in a manner that differs for each individual vane.

Another advantageous specific embodiment of the present invention provides that one individual control be provided in each case for some or all of the guide vanes. This makes it possible to individually correct in the case of altered flow conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The following includes a more detailed explanation of other refinements of the present invention, along with the description of a preferred exemplary embodiment of the present invention, with reference to the figures, which show:

FIG. 1: a schematic representation of an inlet guide baffle in accordance with the present invention;

FIG. 2: a schematic representation of a related-art inlet guide baffle;

FIG. 3: a schematic representation of a further embodiment of the present invention; and

FIG. 4: a schematic representation of adjustable guide vanes according to yet a further embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 shows a schematic representation of a developed view of an inlet guide baffle 20 in accordance with the present invention having multiple profiles, i.e., of individual profiling of each individual vane of the inlet guide baffle. In this manner, the vanes are adapted to the variable circumferentially asymmetric angle of incidence of the inlet guide baffle. This asymmetrical incident flow is caused by the asymmetric air inlet 10, shown schematically. The inlet guide baffle according to the present invention produces a constant outflow angle over the entire periphery, and substantially circumferentially symmetrical inlet conditions are passed onto the first compressor stage. This leads to an improved stability and an enhanced efficiency of the compressor.

FIG. 2 shows a schematic representation of a developed view of an inlet guide baffle according to the related art, having a circumferentially asymmetrical incident flow that is caused by an asymmetric air inlet. Here, the extreme left and extreme right guide vanes in the drawing plane exhibit flow separations which propagate into the downstream compressor stages and lead to unstable compressor performance, i.e., to surging. It is also discernible in FIG. 2 that the outflow angle in this case is not constant over the periphery, rather that it changes at each guide vane, which may likewise lead to unstable compressor performance and efficiency losses.

FIG. 3 shows a further embodiment with an inlet guide baffle 100 which provides substantially circumferentially symmetrical inlet conditions, but has an intermediate guide baffle 120. Due to the asymmetric profiling of the intermediate guide baffle following the inlet guide baffle, any residual asymmetries of the flow possibly still existing may be further reduced following the first stage.

FIG. 4 shows a further embodiment in which the guide vanes be formed on the inlet side of a fixed component 102 and, on the outlet side, of a pivotable component 112. In this manner, even individually differing profilings may be created for individual vanes of the guide vane baffle when some or all of the vanes are suitably adjusted in a manner that differs for each individual vane. A controller 1000 can be provided for adjustment.

The present invention is not limited in its practical implementation to the preferred exemplary embodiment indicated above. Rather, a number of variants, which utilize the approach described in the patent claims, are conceivable, even in the context of fundamentally different executions. 

1-8. (canceled)
 9. An axial flow machine comprising: an asymmetrical air inlet; and a compressor downstream from the asymmetrical air inlet, the compressor having an inlet guide baffle composed of guide vanes, at least some of the guide vanes of the inlet guide baffle having a vane profile and/or an angle of attack deviating from other remaining guide vanes, a constant outflow angle being produced over an entire periphery by the inlet guide baffle.
 10. The axial flow machine as recited in claim 9 wherein some or a plurality of further guide baffles downstream from the inlet guide baffle have at least some guide vanes having a vane profile and/or an angle of attack deviating from the remaining guide vanes.
 11. The axial flow machine as recited in claim 9 wherein individual guide vane groups formed by the at least some of the guide vanes have the vane profile and/or angles of attack deviating from the other remaining guide vanes.
 12. The axial flow machine as recited in claim 11 wherein the guide vanes of the inlet guide vane groups have vane profiles and/or angles of attack that deviate from one another.
 13. The axial flow machine as recited in claim 9 wherein all of the guide vanes are differently profiled and/or have a different angle of attack.
 14. The axial flow machine as recited in claim 9 wherein at least some of the guide vanes have an adjustable design.
 15. The axial flow machine as recited in claim 9 wherein at least some of the guide vanes are formed on the inlet side of a fixed component and, on the outlet side, of a pivotable component.
 16. The axial flow machine as recited in claim 14 further comprising one individual controller for some or all of the guide vanes having the adjustable design.
 17. The axial flow machine as recited in claim 15 further comprising one individual controller for some or all of the guide vanes having the pivotable component.
 18. An axial flow machine comprising: an asymmetrical air inlet; and a compressor downstream from the asymmetrical air inlet, the compressor having an inlet guide baffle composed of guide vanes, at least some of the guide vanes of the inlet guide baffle having a vane profile and/or an angle of attack deviating from other remaining guide vanes to provide a more constant outflow angle over an entire periphery by the inlet guide baffle, the more constant outflow angle containing residual assymetries; and the compressor further including a further guide baffle downstream from the inlet guide baffle, the further guide baffle having at least some guide vanes having a vane profile and/or an angle of attack deviating from the remaining guide vanes of the further guide baffle to compensate for the residual assymetries. 